Analysis of characteristic x-ray generation induced by laser plasma electrons accelerated by an electric field

The results of experiments devoted to the study of spectral, spatial, and t ime characteristics of a spectrally bright point x-ray source based on a va cuum diode with a laser-plasma cathode and a titanium needle anode with a p hoton energy approximately equal to 4.5 keV are presented. The experimental results revealed a considerable difference between the electron emission f rom laser plasma in a strong electric field and the explosive electron emis sion and demonstrated the effectiveness of laser plasma as an electron sour ce. The optimization of the laser radiation power density, the accelerating voltage, and the interelectrode spacing made it possible to create a point x-ray source whose spectral brightness exceeds available sources in the cl ass of small-size pulse x-ray instruments (tubes with explosive cathodes). It has been proved experimentally that the maximum contrast of the characte ristic lines of the anode material is attained in the case of an optimal ch oice of accelerating voltage. The x-ray source has the following parameters : (1) spectral brightness of the K-lines of titanium of the order of 10(21) photons/cm(2) s sr keV; (2) emitting region size of 250 mum; and (3) laser pulse duration less than 20 ns. (C) 2001 MAIK "Nauka/ Interperiodica".